Gastric pepsin, mucus and clinical secretory studies. II. The role of the mucous barrier in the defense of the stomach vs. peptic ulceration. Carbohydrate histochemistry of gastric epithelial secretions in dog.

Abstract

SummaryHistochemical methods specific for carbohydrate constituents distinguish a number of widely different entities in several types of gastric epithelial cells in the dog.The surface gastric epithelium reveals basophilia, indicating mucosubstances rich in both carboxyl groups (presumably sialic acid) and sulfate esters. The carboxyl‐type basophilia predominates in the superficial convolutions, and that attributed to sulfate is found in the foveolar walls. The strong reactivity with both the periodic acid‐Schiff (PAS) and the periodic acid‐para diamine (PAD) methods for vicinal‐hydroxyls indicates presence of hexose‐ or deoxyhexose‐rich mucosubstances in both of these areas. Susceptibility of basophilia to blockage by initial periodate‐meta diamine treatment points to presence of vicinal‐glycols in proximity of the acid groups in surface epithelium mucin. The surface epithelium in the pylorus differs slightly in that its secretion is less strongly basophilic.The mucous neck cells secrete an apparently neutral mucosubstance which differs from the surface epithelium in its lack of both PAD reactivity and basophilia. The parietal cells also form a diastase‐resistant, neutral, carbohydrate‐rich substance. The zymogen cells are abundant, deep in the glands of the cardiac portion and the body of the stomach, but less numerous in the intermediate zone. They contain apical granular secretion apparently rich in sulfated mucosubstances. Lack of reactivity toward vic‐glycol methods, resistance of alcianophilia or azurophilia to a previous periodate‐meta diamine sequence, and resistance of mixed diamine staining to previous periodate oxidation indicate absence of residues with unsubstituted adjacent hydroxyls (e.g., hexose or deoxyhexose), in this acid mucosubstance.The pyloric glands resemble mucous neck cells in their strong PAS staining and lack of PAD reactivity, but differ in that they show a weak staining indicative of sulfomucin.